This program in studies on prematurity has focused in its clinical research on the recognition of intrauterine growth retardation prior to delivery, the management of such pregnancies, and the description of the morbidity, both acute and long-term, associated with intrauterine growth retardation. In basic research the focus has been primarily around studies in fetal nutrition, defining the substrates which the fetus uses for growth and development with the mother in both the fed and starved states. In addition, the regulation of uterine blood flow in both pregnant and nonpregnant animals has been investigated with radioactive microspheres and with chronically implanted electromagnetic flow probes. The effects of catecholamines and a variety of estrogens upon uterine blood flow and its distribution to the uterus have been studied. In addition, studies have been carried out on amino acid transport across trophoblast and upon the cell-surface glycoproteins which can be isolated from trophoblast.